Australian Jessica McNamee will play Rachel McAdams' estranged younger sister in "
The Vow," Screen Gems and Spyglass' romantic drama being directed by Michael Sucsy.
"Vow" tells the real-life story of a newlywed New Mexico couple (McAdams and Tatum) who end up in a car crash. The wife is put in a coma, and when she comes to -- without any memory of her husband or their marriage -- the husband attempts to wins her heart again.